Follicular lymphoma cells exhibit defective T-cell synapse formation with autologous antigen-pulsed tumor cells. (A) Healthy age-matched donor T cells (healthy) or tumor-infiltrated T cells from FL, transformed DLBCL (t-FL), or de novo DLBCL (DLBCL) patients, were allowed to conjugate with autologous healthy B, FL, t-FL, or DLBCL cells, respectively, ± sAg as APCs (CMAC dyed, blue). Conjugates were then fixed and stained with rhodamine phalloidin to detect F-actin (red). Conjugates were selected at random for imaging and were scored for F-actin polarization at the immune synapse. Each dataset is the mean ± SD from 5 independent patient experiments (t-FL and DLBCL, n = 3) with at least 50 conjugates analyzed per experiment. The confocal images shown are CD4⁺ T cells. (B) Healthy age-matched T cells, nonleukemic-phase FL peripheral blood (PB) T cells, leukemic-phase FL PB T cells, and lymph node (LN) tumor-infiltrated FL T cells were allowed to conjugate with stimulated allogeneic healthy APCs (sAg pulsed or CD40 ligated; CMAC dyed, blue). Conjugates were then fixed and stained with rhodamine phalloidin to detect F-actin (red). Conjugates were selected at random for imaging and were scored for F-actin polarization at the synapse. Each dataset is the mean ± SD from 3 independent patient experiments with at least 50 conjugates analyzed per experiment. Original magnification ×63.